VGM Player project for AVR mcu

by Fabien Batteix (alias SkyWodd)

Overview

Work in progress

This project is a VGM (Video Game Music) player based on a ATmega644/1284 AVR mcu.

This project used two sounds chip from the Megadrive game console :

• The SN76489 PSG sound chip (for noise and square waves)
• The YM2612 FM sound chip (for complex sounds emulation, like piano)

For more detail on the hardware design please take a look at my blog (URL just below my github name).

Hardware

Basic

• ATmega644 (64K flash, 4Ko RAM) or ATmega1284 (128K flash, 16Ko RAM) AVR mcu running at 16MHz
• FTDI basic module for Serial communication with host PC
• ICSP header for programmation
• 1x 23LC1024 SPI SRAM for VGM file storage

Human-computer interface

• 4x20 serial LCD from Sparkfun
• 3 leds (Yellow for RAM access, Red for "pause", Green for "playing")
• 3 buttons (disable/enable PSG sound chip, disable/enable FM sound chip, Play/Pause)

Audio

• 1x YM2612 FM sound chip (Yamaha)
• 1x SN76489 PSG sound chip (Texas Instrument)
• Analog front-end for mixing and speaker output

Dynamic clocking

• 2x LTC6903 (SPI version) for dynamic clocking of sound chips

For pins mapping please take a look at header file: "pinmap.h".

Software compatibility

• XMODEM (with CRC-16) for VGM file transfert over the serial link
• VGM 1.61 (and earlier) for music playback
• GD3 1.0 for track informations (only english strings are used)

For more informations please see:

• http://www.smspower.org/uploads/Music/vgmspec161.txt
• http://www.smspower.org/uploads/Music/gd3spec100.txt

Test code for sound chips

Fake YM2612 and SN76489 are common on ebay. To chek if your YM2612 or SN76489 are fake or not two test code are provided.

• One for the YM2612 who play the same note again and again infinitly.
• One for the SN76489 who play some notes on all channels sequencialy in an infinite loop.